SAR interferometry with OTB

Usage
#1

Dear all, Are there any documents or examples about SAR interferometry with OTB？

I am a researcher on SAR interferometry algorithms for over ten years and I am very excited to hear that OTB can do the job like ISCE or GAMMA etc. But I found it is hard to start as SAR interferometry is quite a long chain of algorithms to follow and the The configure files of diapOTB python scripts are not documented well. I believe someone has suceeded in SAR interferometry with OTB but the topic is seldom discussed here. Can someone kindly give me some advice?

Specifically:

  • In configure file ex_config_diapOTB_S1IW.json 
	"in": 
	{
	    "Master_Image_Path": "image_1.tif",
	    "Slave_Image_Path": "image_2.tif",
	    "DEM_Path": "DEM.hgt"
	},

How to prepare the .tif and .hgt files?

Thanks for Reading and Best Regards.:slight_smile:

#2

Hi,

I don’t know about interferometry, but I can help with DEM.

In OTB applications, the DEM path must be a directory that contains rasters. You can put your .hgt files in this directory. I believe that since OTB 5 or 6, other raster formats are also supported as DEM (e.g. GeoTiff, …).
Also, you can take a look to the DowloadSRTMTiles application that will automatically download the SRTM tiles for you!

Hope that helps,

Rémi

1 Like
#3

Thanks for your reply Rémi!
But when I read the source code below to deal with the input hgt file, I think the “DEM.hgt” metioned above is not just a hgt file that downloaded with the DowloadSRTMTiles.

def getDEMInformation(dem):
    """
        Retrieve DEM information thanks to ReadImageInfo
    """
    # Get information about DEM (spacing, size ..)
    ReadDEMInfo = otb.Registry.CreateApplication("ReadImageInfo")
    ReadDEMInfo.SetParameterString("in", dem)
    ReadDEMInfo.SetParameterString("keywordlist", "true")
    ReadDEMInfo.Execute()

    dictDEMInformation = {}
    dictDEMInformation['spacingXDEM'] = ReadDEMInfo.GetParameterFloat("spacingx")
    dictDEMInformation['estimatedGroundSpacingXDEM'] = ReadDEMInfo.GetParameterFloat("estimatedgroundspacingx")
    dictDEMInformation['spacingYDEM'] = ReadDEMInfo.GetParameterFloat("spacingy")
    dictDEMInformation['estimatedGroundSpacingYDEM'] = ReadDEMInfo.GetParameterFloat("estimatedgroundspacingy")

    return dictDEMInformation

The keywords above such as “spacingx” were not metioned before, There must be a auxilliary file with it.

Thanks again!

Wei

#4

Note that the DownloadSRTMTiles application is currently broken (see Broken links in DownloardSRTMTiles (#2164) · Issues · Main Repositories / otb · GitLab) because the download portal now require authentication to download the data.

1 Like
#5

Yes, it is. I’ve downloaded the SRTM tiles manually. Thanks for your friendly reminder，julienosman.

The official site dimonstrated attrative pictures produced by DiapOTB.

974×652

But it is hard to follow.

#6

Hello,

I can’t really help you on interferometry but you can have a look at the documentation of the diapotb module if you haven’t found it already. The doc is a bit light, but this page might help you.

Cédric

#7

Thank you very much for your help， Cédric.
I have read the documentation already and it is really helpful to establish a general view of the DIapOTB. SAR interferometry is quite a long chain of algorithms to follow and preparations for the inputs are not mentioned there. I think examples might be more useful for a starter.

Best regards!

Wei